Answer:
c=40
Explanation:
a + c=65 equation 1
7a+4c=335 equation 2
c=65-a isolate c from equation 1
7a+4(65-a)=335
7a+260-4a=335
3a=75
a=25
solve for c
a+c=65
25+c=65
check answer:
7a+4c=335
7(25)+4(40)=335
175+160=335
335=335
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